Dr Mark Edwards says the cells in our eyes are more sensitive to the lime green, especially at night.

ABC News: Mark Moore

I wanted to know if there was a scientific reason why the colour yellow stood out more at night.

Dr Mark Edwards is an associate professor at the Australian National University's school of psychology.

He explained that we have two different types of cells that are sensitive to light and help us see - cones for colours and rods for brightness.

Biologically we are more attuned to seeing blue and green at night.

"By having red fire engines, that's great in the day time conditions because our cones can see that in a vivid way, but in low light conditions or twilight conditions the rods are just insensitive to red fire engines," he said.

"Whereas if it's a lime green fire engine, that's in the sweet spot of the sensitivity of the rods so that will then feed into our sense of brightness and it'll just be a lot more easy to see those lime green fire trucks."

He said the fact that people may not be used to seeing lime green engines shouldn't be problematic.

"You'll still see it, but it may take you a little longer to realise it's a fire engine.

"Of course it's got flashing lights and a siren, so you'd know it'd be a good idea to get out of it's way.

"But in terms of detecting it, it (the colour) will have no impact on your ability to detect it."

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